Crystal Structure and Superconductivity of the solid solution system Sm_xBa_1-xCuO_y

Abstract

The Sm_xBa_1-xCuO_y system has been investigated by powder X-ray diffraction, electrical resistivity (R) and thermogravimetric analysis (TGA) measurements. This system forms a solid solution in the composition range 0.33≤x≤0.50. With increasing x, this system undergoes a phase transition from the orthorhombic to tetragonal structure around x≅0.41. The temperature dependence of R shows two step drops (Tc₁, Tc₂) toward zero resistivity on cooling, which behavior is very similar to the one observed in YBa₂Cu₃O_y. Tc₂ gradually decreases through the orthorhombic to tetragona phase.